1. Field of the Invention
The present invention relates to the field of liquid crystal display technology, and in particular to an alignment film and the manufacturing method for liquid crystal display panel.
2. the Related Arts
The development of information society increases the demand towards the display devices. In order to meet this demand, a lot of flat panel display devices, such as liquid crystal display (LCD), plasma display (PDP), OLED display, etc., have been developed rapidly. Among all of the flat panel display, liquid crystal display device is gradually replacing the cold cathode display device due to its low weight, small size and low power consumption.
For the vertical alignment display mode, a liquid crystal display device is mainly composed of the two substrates and, negative liquid crystal molecules embedded between two substrates visualized as a biscuit. The characteristic of multi-domain vertical alignment mode (MVA) is forming rib with a certain shape at the color film side. Patterned vertical alignment mode (PVA) does not need to form the rib at the color film, but it forms the corresponding ITO slit on the transparent conducting oxide at the color film side. However, in the above two techniques, the transmittance of rib and ITO slit is much smaller than that of the normal pixel area, which would affect the transmittance of the overall product. The advantage of polymer sustained vertical alignment (PSVA) is that reactive monomer is added into the negative liquid crystal. These reactive monomers will react according to a certain law through the external influences. Transparent electrode with smaller width and transparent ITO slit are used on the side transparent electrode array pattern.
The display modes mentioned above have its own characteristics, and it was widely produced. But the transmittance of rib and ITO slit is much smaller than the transmittance of the normal pixel area, which would affect the transmittance of the overall product. For PSVA display mode, the reactive monomer is not only expensive, but also it can form dropping mura easily with the one drop fill (ODF) process, which mainly refers to low contrast, uneven brightness, and surface area greater than one pixel defects. At the same time, different batches of liquid crystal material have more or less different concentration of reactive monomer during mass production, which would form the display mura on the final product easily. During the photo-alignment process, the liquid crystal cell at particular position will react very fast, forming some large reactants and resulting in broken light issues.